Process for the production of glass

Abstract

The present invention relates to a process for production of a glass by the vacuum melting method using silica as raw material and comprises uniformly preheating a silica powder containing an accelerator for phase conversion to about 800° C.; filling the preheated silica powder in a container while substantially maintaining the temperature; further heating the silica powder to convert it into a sintered body having a cristobalite phase; and then heating and melting the sintered body in vacuum for glass formation, whereby not only are improvments in raw material efficiency and productivity by shortening of the heating time achieved, but also the formation of cracks on the surface of the resulted sintered body which has been one of the important reasons for resulting in products of sub-standard can be substantially completely avoided.

We claim: 
     
       1. A process for the production of a glass, characterized in that silica powder containing an accelerator for phase conversion is uniformly preheated up to a temperature of about 800° C., said preheated silica powder is filled in a container while substantially maintaining said temperature, further heating said silica powder to convert it into a sintered body having cristobalite phase, and heating and melting said sintered body in vacuum for glass formation. 
     
     
       2. A process for production of a glass as claimed in claim 1, characterized in that the preheating of the silica powder is carried out by heating the silica powder while stirring. 
     
     
       3. A process for production of a glass as claimed in claim 1, characterized in that in said further heating, the temperature of the sintered body is maintained for a predetermined period of time just before the start of sintering.